Recording mercury-barometer.



G. AGOLINI. RECORDING MERCURY BAROMETBR. APPLICATION FILED SEPT. 25,1911. 1,068,726, Patented July 29, 1913.

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Patented July 29, 1913.

G. AGOLINI. RECORDING MERCURY BAROMETER.

APPLICATION FILED SEPT. 25, 1911.

1,068,726, Patented July 29, 191 3.

5 SHEETS-SHEET 3. 9 10 FEM] 11 c0LUMi|A PLA NOORAPH CO WASHINGTON, D. c.

G. AGOLINI.

RECORDING MERCURY BAROMETER.

APPLICATION FILED SEPT. 25, 1911.

Patented July 29, 1913.

5 SHEETSSHEET 4.

G. AGOLINI.

RECORDING MERCURY BAROMETER.

APPLIOATION FILED SEPT. 25, 1911.

COLUMBIAPLANDDRAPH 60.. WASHINGTON. D. cv

Patented July 29, 1913.

5 SHEETS-SHEET 5.

PT HIE.

GIUSEPPE AG-OLINI, 0F TURIN, ITALY.

RECORDING MERCURY-BAROMETER.

To all whom it may concern:

Be it known that I, Grnsnrrn AGOLINI, a subject of the King of Italy,residing at Turin, Italy, have invented certain new and usefulImprovements in Recording Mercury- Barometers; and I do hereby declarethe following to be a full, clear, and exact description of theinvention such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawings, and to letters or figures of reference markedthereon, which form a part of this specification.

This invention has for its object to provide an improved recordingmercury barometerin which the variations of level of the barometriccolumn are recorded in the form of a continuous diagram on a sheet ofpaper wound on a drum, to which uniform rotation is imparted by means ofan ordinary clock mechanism.

- The recording mechanism of the improved mercury barometer comprises afloat floating at the surface of the mercury column, 0., inside thebarometer chamber (Torricellian chamber). This float is attached to arigid rod extending through the mercury column and connected at itslower end to transmitting device situated outside the barometer tube. Tothis device is connected the stylus for drawing the diagram on therecording drum.

Some forms of execution of a recording barometer according to thisinvention are illustrated by way of example in the accompanyingdrawings, in which:

Figure l is a vertical section of the general arrangement of a firstform of construction of the barometer; Fig. 2 is a vertical section on alarger scale of the barometer chamber alone; 3 is a vertical section atright anglesto Fig. 2 of the upper part only of the barometer chamber;Fig. 4 is a plan of the barometer chamber; Fig. 5 is an elevation on alarger scale of the lower part of the barometer tube. Figs. 6, 7, 8 and9 illustrate details. Fig. 10 is a vertical sec tion of the generalarrangement of a second slightly modified form of the same barom' eter.Fig. 11 is a vertical section of the barometer chamber alone on a largerscale. Fig. 12 is an elevation of the lower part of the barometer tubealso on a larger scale.

Specification of Letters Patent.

Application filed September 25, 1911.

Patented July 29,1913.

Serial No. 651,159.

Figs. 13 to 15 are details. Fig. 16 is a detail view of the recordingdrum.

One form of recording barometer constructed in accordance with thisinvention, and illustrated in Figs. 1 to 9, comprises a barometer tube1, preferably of steel or iron fixed to the upright 2. This tube 1communicates at its upper end with the barometer chamber 3 (Torricellianchamber) which is likewise made of iron or steel and consists preferablyof a bottom 3 having an annular mortise in which engages the cylindricalchamber 3 which is fixed to the corresponding annular groove of thebottom 3 by means of a cement having a melting point of about 80 (1.,for the purpose of enabling the barometer chamber to be removed forcleaning its interior. The tube 1 is immersed at its lower end into awell or tube 4: provided with a discharge cook a. This well 4communicates normally with a basin 5 (constituting the base of theapparatus and provided with screw feet 6 for supporting and levellingthe apparatus) through slots 4 formed in the side of the well l andthrough corresponding slots 7 formed in an obturating device 7 havingthe form of a ring capable of turning with slight friction on theoutside of the tube l. This communication may, however, be interruptedtemporarily by turning the ring 7 as shown in the details Fig. 8, insuch a manner as to close the slots 4 by means of the full portions ofthe ring 7. The barometer chamher 3 may be placed in communication withthe atmosphere at its upper end by means of a hole 8 and a cock 9,inclosed in a cyl-. indrical Vessel 10, preferably of glass, whichextends up beyond the outlet 9 of the cock 9, and is removably mountedon the upper end of the chamber 3. The vessel 10 is provided with adischarge cook 11.. Inside the barometer chamber 3 is a plate 12 ofsuitable material, (for instance ebonite) which, as hereinafterdescribed, floats on the surface of the mercury column and consequentlyfollows the variations of level of this column inside the chamber 3. Atthe center of this plate 12 is fixed a rod 13 preferably of steel,extending vertically down in the axis of the barometer tube 1. Its lowerend projecting from the tube 1 terminates in a plate l i provided with apacking 15 preferably of eaoutchouc. For the purpose of guiding thesliding apparatus which comprises the plate 12 and its rod 13 during itsvertical movements, the plate 14 is provided with a certain number ofbars 16 (four are employ d in the example) which extend vertically upoutside the tube 1 and are connected together by means of two rings 17,preferably of aluminium, encircling the tube 1. These rings are suitablyspaced apart and are provided all round with a certain number of rollers18 hearing against the outer surface of the tube 1. shown in detail inFigs. 6 and 7, in elevation and plan respectively. Owing to this methodof suspension and guidance the sliding apparatus does not encounter anyappreciable resistance to its movements.

To one of the bars 16 of the sliding apparatus (said bars having asuitable length for passing entirely out of the well 4 and for passingbeyond the top of the cover 5 of the basin 5) is rigidly connected ahorizontal arm 19 provided at its end with a stylus 20 for drawing thediagram 21 of pressures on a sheet of paper wound on the drum 22 whichis continuously rotated by means of an ordinary clockwork. The positionas to height of the arm 19 along the bar 16 to which it is fixed is suchthat the diagram 21 drawn by the stylus will be situated about mid-wayup on the drum 22, when the outer barometric pressure is normal. Anotherhorizontal arm 23 provided at its end with a stylus 28 for drawing aline 24: on the drum 22 is connected by means of a rod 25 capable ofvertical motion to a plate 26 which acts as a float floating on thesurface of the mercury contained in the basin 5 (shown in detail in Fig.9). By this means the line 21 drawn by the stylus 23 indicates the levelof the mercury in the basin 5 and thus constitutes the base line of thediagram of pressures 21 drawn by the stylus 20.

It is to be noted that any suitable material may be employed in theconstruction of the various parts of the apparatus. For the partsintended to come in contact with mercury recourse must naturally be hadto materials which are unaffected by mercury such as glass, wood,ebonite, etc, and among metals, iron, steel, etc. The selection of oneor the other of these materials will depend naturally on the shape andnature of each part of the construction. As regards the dimensions ofthe barometer there is no limit from a constructional point of view withthe exception of the distance about 7 6 cm. (height of the barometriccolumn)- between the level of the mercury in the basin 5 and that of themercury in the chamber 3, in which the mercury should stand at abouthalf way up when the atmospheric pressure is normal. It will, however,be well to make the proportion between the cross sections of the chamber3 and that of the basin 5 very One of these rings is high for instance1:100, with the object of rendering inappreciable the variations oflevel of the mercury in the basin 5 consequent on the variations oflevel of the mercury in the chamber 3. lVith a ratio of 1:100 thevariations of level in the basin 5 are entirely inappreciable, so thatthe base line 24L of the resulting diagram will be a straight line.

The mercury is introduced into the barometer as follows: First, thelower exit of the tube 1 is closed by raising the sliding apparatusuntil the caoutchouc packing 15 of its plate 14 abuts against the lowerend of the tube 1. Then the suction pipe of a pump is applied to theoutlet 9 of the previously opened cock 9, for the purpose of producingthe highest possible vacuum in the interior of the parts 1 and 3. Theslots 4 of the part 4 are then closed by moving the ring 7 as shown inFig. 8, and the well 4- is filled with mercury. T hen the lower end ofthe tube 1 is opened slowly by slightly depressing the sliding apparatusand this causes the mercury to rise in the tube 1. By continuing theoperation of the pump and keeping the well 4 always full of mercury,this mercury is caused to rise slowly above the plug of the cock 9. Thenthe cock is closed and after having removed the suction pipe of thepump, the vessel 10 which had been previously removed is placed again inposition and filled with mercury until the cock 9 and its outlet 9 arecompletely submerged. Then the slots 1' are opened by turning the ring7, and the mercury contained in the well 1 sinks into the basin 5, thuscausing the mercury in the chamber 3 also to sink to its normal level,leaving behind it an absolute vacuum apart from mercury vapors. Allentrance of air into the barometer chamber 3 through the cock 9 isprevented by the fact that the cock is submerged by the mercurycontained in the vessel 10.

From the foregoing it will be easy to understand the operation of theapparatus. It must first be noted that owing to the difference in thespecificgravities of the mercury and the metal parts constituting thesliding apparatus, the latter is subjected to an upward thrust. Theconstruction of this sliding apparatus is such that the weight of itsparts which are not submerged in the mercury, such as the upper parts ofthe bars 16, the rings 17, the arm 19, etc, shall be approximately equalto the said upward thrust. The sliding apparatus will therefore be inequilibrium as a whole when the plate 12 bears on the surface of themercury contained in the chamber Consequently the plate 12 will followaccurately (more by virtue of adhesion than by the action of the weightacting upon it) allthe variations of level of the mercury inside thechamber 3.

These variations will betransmitted accurately and in their exactamounts to the stylus 20, which will thus mark the eXact diagram ofpressures upon the piece of paper that is wound on the drum 22..

The modifications which occur in the slightly modified form of barometerillustrated in Figs. 10 to 16 are substantially as follows: Thebarometer tube 1 is freely supported by a crosspiece 2 fixed to uprights2 and is provided with two stops 1' for the attachment of a thermometer.The plate float 12 of the sliding apparatus is made slightly convex atits upper part for the purpose of preventing small particles of mercuryfinding a lodging thereon. Screw foot 6 are mountedon balls 6, and acircular spirit level 27 is provided on the cover 5 for the purpose ofleveling the barometer. The valve for temporarily closing the end of thetube 1, when introducing the mercury in the apparatus, is preferablymade in the form shown in Figs. 13 and 1 1. This valve consists of aplug 28, preferably of rubber, for closing the tube 1 and is threaded ona rod 13 by means of its central hole which has a diameter slightlygreater than that of the rod 13. This hole ends at its lower part in aflaring conical portion 28, in which is adapted to engage a conical plug29, also of rubber, fixed to a cross 14 to which outer bars 16 areattached. The rod 13 is also provided above the plug 28 with a washer30. After a vacuum has been established in the tube 1, the slidingapparatus is lowered slightly in order to effect the introduction of themercury. The plug 29 is lowered and the mercury, in passing through theannular space between the rod 13 and the central hole in the plug 28,strikes against the washer 30, which moderates the force of the jet anddeflects the mercury toward the inner sides of the tube 1, along whichthe mercury rises slowly, carrying up with it any particles of rarefiedair which may be still adhering to the tube 1. The recording mechanismhas also been slightly modified. For instance a retaining part 31 (Fig.12) is provided for keeping the stylus 20 in contact with the drum 22.Further the arms 19 and 23 connected respectively to the slidingapparatus and to the rod 25 are mounted adjustably as to height by meansof adjusting screws 19 and 23 respectively. The position of the drum 22as to height is further adjustable by means of the adjusting screw 32acting upon the arm 22 supporting the drum. A datum pointer 33 is fixedin an invariable position on the cover 5 (Figs. 10 and 16). All theseslight modifications are for the purpose of facilitating the setting ofthe barometer and the mounting upon the drum 22 of the sheet of paper onwhich are drawn horizontal and parallel pressure-indicating lines spaceduniformly apart, for instance at a distance of 1 mm. and verticalparallel and equidistant time lines, and also a horizontal line servingas the base line of the diagram.

At the first mounting of the sheet upon the drum 22 the operation is asfollows: The base line of the sheet is made coincident with the pointer33 by adjusting the height of the drum 22 by means of the screw 32. Thenthe position of the part 23 as to height is regulated bymeans of a screw23 in such a manner as to cause the stylus 23 to coincide with the baseline. Then by means of the part 19 the position at the height of thestylus 20 of the part 19 is adjusted until this stylus coincide with theline of the diagram which corresponds with the pressure indicated by astandard barometer at the time of starting the improved instrument. Thenthe clockwork of the drum 22 is wound up, and after having brought thetime line marked on the sheet of paper corresponding to the hour atwhich .the improved instrument is started, opposite the two styluses 20,23 the drum is started. Then when it is required to replace a filled upsheet by a fresh sheet, there is no need of again having to obtain thereading of the atmospheric pressure from a standard barometer as abovestated, it being sufficient to bring the base line of the diagramopposite the pointer 33 and the corresponding time line opposite the twostyluses 20, 23. It is preferable to employ the intermediate pointer 33for setting the sheet of paper, rather than the stylus 23, in order toavoid soiling the sheet of paper. In mounting the sheet of paper, it ispreferred to move the two styluses 20, 23 away from the paper byshifting by means of a knob 34:, the vertical rod 35, which bearssimultaneously against the arms 19, 23.

The chief advantages of the improved recording barometer may be summedup as follows: This barometer compared with existing barometers is veryaccurate, because in it there are eliminated the depression due tocapillarity and also the inconstancy of the meniscus formed by thesurface of the mercury in the barometer chamber which varies veryappreciably in existing barometers according as it is produced by anascending or a descending movement of the barometric column. In thisbarometer there is also eliminated the operation of reducing to zero andthe operations of carrying the level of the mercury in the basin to adetermined height. The improved barometer also eliminates the personalerror in reading, whilst it allows of recording all the variations ofpressure which are continually taking place in nature.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be per-' formed, I declarethat what I claim is l. A barometer comprisingintercommunicatingcontainers, bodies of mercury therein, one body of small volume ascompared with the other and under vacuum, and mechanisms operated by thevariations of level of both of said bodies of mercury to indicatevarying atmospheric pressure, the mechanism operated by the larger bodyhaving an inappreciable movement due to said variations in atmosphericpressure.

2. A barometer comprising two mercury containers of diiierent volume, abarometric tube normally communicating with said containers, the smallercontainer being maintained under vacuum and the larger container underatmospheric pressure, mechanism for indicating the level of the mercuryin the larger container, and mechanism operable by the mercury in thesmaller container for indicating the variations of the mercury in thesmaller container relatively to the level of the mercury in the largercontainer.

3. A barometer comprising two mercury containers of different volume, abarometric tube normally communicating with said containers, the smallercontainer being maintained under vacuum and the larger container underatmospheric pressure, mechanism operable by the mercury in the largercontainer for indicating the level of the mercury in the latter, andmechanism operable by the mercury in the smaller container forindicating the variations of the mercury in the latter, relatively tothe level of the mercury in the larger container.

4. A barometer comprising two mercury containers of different volume, abarometric tube normally communicating with said containers, the smallercontainer being maintained under vacuum and the larger container underatmospheric pressure, a sliding mechanism on the tube dipping into themercury of the basin, the weight of said mechanism being substantiallyequal to the upward thrust exerted thereon by the mercury, a float inthe smaller container connected with the slide, an indicator carried bythe latter, and an indicator controlled by the mercury in the largercontainer.

5. A barometer comprisinga mercury containing chamber, a mercurycontaining basin of larger volume than the chamber and having a normallycommunicating well extending above and below the bottom thereof, abarometric tube communicating with the chamber and well and extendinginto the latter below the bottom of the basin, means to closecommunication between the basin and well, and means to temporarily closethe lower end of the tube whereby a vacuum may be created in the tubeand chamber.

6. A barometer comprising a mercury conlatter below the bottom of thebasin, means to close communication between the basin and well, means totemporarlly close the lower end of the tube whereby a vacuum may becreated in the tube and chamber,

means to openand close the upper end of the chamber, andmeans to sealthe upper end of the latter.

7 A barometer comprising a mercury containing chamber, a mercurycontaining basin of larger volume than the chamber and having a normallycommunicating well extending above and below the bottom thereof, abarometric tube communicating with the chamber and well and extendinginto the latter below the bottom of the basin, means to closecommunication between the basin and well, a cock in the top of thechamber, and a mercury seal surrounding the cock.

8. A barometer comprising a mercury containing basin, a well projectingthrough and extending'above and below the latter and having aperturestherein near the bottom of the basin, means to close and open theapertures, a chamber above the basin having an exhaust port, abarometric tube projecting into the well and communicating with thechamber, means to close the bottom of the tube, and a valve to open andclose said port.

9. A barometer comprising a mercury containing basin, a well projectingthrough and extending above and below the latter and having aperturestherein near the bottom of the basin, means to close and open theapertures, a chamber above the basin having an exhaust port, abarometric tube projecting into the well and communicating with thechamber, means to close the bottom of the tube, a valve to open andclose said port, and means to form a liquid seal around said valve.

10. A barometer comprising a mercury containing basin, a well projectingthrough and extending above and below the basin and provided withapertures .near the bottom of the basin, a mercury containing chamberhaving an exhaust port therein, a barometric tube communicating with thewell and chamber, a'coek to control the port, a float in the chamber, arod carried by the float projecting through the tube, a plate on the rodadapted to close the lower end of the tube, and means to close theapertures, for the purpose specified.

11. In a barometer, the combination with a mercury container, abarometric tube communicating therewith, a float in the container, and arod in the tube carried by the float, of an indicating mechanismcomprising rings surrounding the tube, means co11- necting the rod andrings, and anti-friction guide rollers journaled in the rings engagingthe tube.

12. In a barometer, two mercury containers of different volume, abarometric tube adapted to communicate with the containers, a float inone of the containers, a rod extending through the tube and carried bythe float, means operated by the rod to indicate the variations of themercury in the tub-e, a main plug having a central opening through whichthe rod projects, said plug adapted to temporarily close the lower 15end of the tube, a conical plug fixed on the rod below the main plug andadapted to fit into the end of said hole, and a washer fixed on the rodabove the main plug, for moderating the force of the mercury passingthrough 20 said hole.

In testimony that I claim the foregoing as my invention, I have signedmy name in the presence of two subscribing witnesses.

GIUSEPPE AGOLINI.

IVitnesses:

PEDRO GIANoLio, FRANCESCO SIMON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents Washington, D. C.

